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High Impact Event

The High Wind Event of 7 March 2004 in the Piedmont of the Western Carolinas Harry Gerapetritis National Weather Service Greer, SC. High Impact Event. Steeple blown off church in Hickory, NC Widespread grass fires

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High Impact Event

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  1. The High Wind Event of 7 March 2004 in the Piedmont of the Western CarolinasHarry GerapetritisNational Weather ServiceGreer, SC

  2. High Impact Event • Steeple blown off church in Hickory, NC • Widespread grass fires • Barns and mobile homes blown over in Gastonia, NC and an historic church moved off its foundation • Large limbs crashing through roofs in Salisbury, NC • Over 30,000 people without power in Charlotte metro area • Control tower evacuated at Charlotte-Douglas International Airport due to wind gusts of 55 mph • Huntersville, NC man killed by a falling tree limb, and a thirteen year-old boy drowned on Lake Greenwood, SC

  3. Magnitude of Event Largely Unanticipated • Foothills: • .TONIGHT…PARTLY CLOUDY WITH A CHANCE OF RAIN SHOWERS THIS EVENING. VERY WINDY WITH LOWS IN THE MID 30S. NORTHWEST WINDS 20 TO 30 MPH…WITH GUSTS NEAR 50 MPH AT THE HIGHER ELEVATIONS. CHANCE OF PRECIPITATION 40 PERCENT. • Piedmont: • .TONIGHT…PARTLY CLOUDY WITH A 30 PERCENT CHANCE OF RAIN SHOWERS THIS EVENING. WINDY WITH LOWS IN THE MID 30S. WEST WINDS 15 TO 25 MPH. FOUS22 KHKY 071200 KHKY GFS MOS GUIDANCE 3/07/2004 1200 UTC DT /MAR 7/MAR 8 /MAR 9 /MAR 10 HR 18 21 00 03 06 09 12 15 18 21 00 03 06 09 12 15 18 21 00 06 12 N/X 38 55 32 45 27 TMP 66 66 58 51 47 44 40 49 51 52 46 40 37 35 34 40 42 43 40 31 29 DPT 40 36 33 31 27 24 23 24 24 23 22 22 24 23 23 24 26 26 26 24 22 CLD SC SC OV CL CL CL CL CL SC SC CL CL SC SC OV OV OV OV OV OV SC WDR 25 27 30 31 30 30 30 32 32 32 32 32 32 32 33 00 10 05 03 36 35 WSP 09 12 15 15 15 14 12 16 15 13 10 07 06 04 01 00 01 01 03 07 07 P06 27 16 8 4 1 1 3 17 52 27 15 P12 18 4 3 52 31

  4. 500 hPa Eta Forecast at 00 UTC March 8, 2004 500 hPa heights, wind barbs, isotachs

  5. 850 hPa Eta Forecast for 12 UTC March 8, 2004 850 hPa heights, winds, isotachs

  6. Visible Imagery and Surface Observations 20 UTC

  7. 00 UTC March 8, 2004 Greensboro, NC Sounding (GSO)

  8. KGSP Composite Reflectivity 0100 UTC 8 March 2004

  9. Eta Frontogenesis Forecast at 00 UTC 8 March, 2004 850 hPa 2-D Fn, MSLP, 1000-850 thickness

  10. Eta Cross Section Valid at 00 UTC 8 March 2004 Potential temperature, omega, wind barbs

  11. 00 UTC 5 February 2002 Blacksburg, VA Sounding (RNK)

  12. 500 hPa Eta Forecast valid at 00 UTC 5 February 2002 500 hPa heights, wind barbs, isotachs

  13. Eta Cross Section valid at 00 UTC 5 February 2002 Potential temperature, omega, wind barbs

  14. 00 UTC 29 March 2000 Greensboro, NC Sounding (GSO)

  15. Eta 500 hPa Forecast valid at 00 UTC 29 March 2000 500 hPa heights, wind barbs, isotachs

  16. Eta Cross Section valid at 00 UTC 29 March 2000 Potential temperature, omega, wind barbs

  17. SummaryConsider high wind potential if you have: • A deep, surface-based, mixed layer • Dry-adiabatic into the 800-700 hPa layer, or higher • Usually capped by a narrow moist zone with dewpoint depressions 5 degrees C or less • A strong, mid-tropospheric speed maximum • Winds 50 knots or greater at 700 hPa, or top of mixed layer • Winds 100 knots or greater at 500 hPa • Strong downward omega in the lower troposphere • 6 to 9 microbars/second or stronger • Subsidence is often due to cold advection, but frontogenesis or other sources can also contribute

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